Expression of genes encoding neuropeptides and enzymes in the brain, with emphasis on the hypothalamus, are being studied. We successfully created a "knock-out" of the oxytocin gene in mice through homologous recombination. These mice demonstrate that oxytocin is absolutely required for milk ejection, but not mammary gland development, fertility or parturition. We are conducting further studies to see how the absence of oxytocin affects mouse behavior. We are also studying the novel POU protein, RHS2 (Brain-4), whose full-length cDNA we previously cloned. We have mapped the sites of expression, including during development in the mouse, of the four class III POU proteins to further our understanding of their roles. We have also determined that the class III proteins interact with each other in far-western and two-hybrid assays. We have determined that Brain-4 interacts with a nuclear protein that may be involved in RNA processing. We have used the technique of differential display to isolate the genes from pineal gland. One novel gene is also found in the retina and we are trying to determine if it is linked with any human retinal diseases. We are also mapping the distribution of serotonin N-acetyltransferase and hydroxindoyl-O- methyltransferase expression in human and monkey tissues. Dr. Malik, using the expertise he gained from protein expression, developed a novel approach to receptor autoradiography to show a potential site of action of the obesity protein, leptin. Mapping of gene expression in the human hypothalamus continues: analyses of vasopressin, oxytocin, LHRH, and the opioids have been published. Maps of the tachykinins, corticotropin- releasing factor, somatostatin, and growth hormone-releasing factor are in progress.